Thermal relay with improved heater arrangement



1966 w. c. BROEKHUYSEN 3,270,167

THERMAL RELAY WITH IMPROVED HEATER ARRANGEMENT Original Filed Jan. 9, 1963 2 Sheets-Sheet 1 FIG. I

FIG. 3

FIG. 6 62 INVENTOR. WILLIAM C. BROEKHUYSEN BY I I ATTOR NEY ,1966 LC.BROEKHUYSEN 3270J67 THERMAL RELAY WITH IMPROVED HEATER ARRANGEMENT Original Filed Jan. 9, 1963 2 Sheets-Sheet 2 FIG. 8 69 76 FIG 9 73 as s Ax 1% 45a. 490. 76

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8 I IN VENTOR.

WILLIA C. BROEKHUYSEN BY ATTORNEY United States Patent 3,270,167 THERMAL RELAY WITH IMPROVED HEATER ARRANGEMENT William C. Broekhuysen, New York, N.Y., assignor to G-V Controls Inc., Essex County, N.J., a corporation of New Jersey Continuation of application Ser. No. 250,447, Jan. 9, 1963. This application July 13, 1965, Ser. No. 475,310

14 Claims. (Cl. 200122) This application is a continuation of my pending application Serial No. 250,447, filed January 9, 1963, now abandoned, and entitled, Thermal Relay.

This invention relates to a thermal rel-ay-i.e. to a relay having a heater member and having out-put contacts whose relations-hip to each other is to be altered by the electrical energization of that member. The output contacts may be arranged to be closed (from normally open relationship) or opened (from normally closed relationship) at the expiration of a time interval from the inception of energization of the heater member, the relay then performing a time-delay function; alternatively the contact condition may be arranged to be altered only 'when the energization of the heater member undergoes a unidirectional ldeviation which is appreciable (taking into account both magnitude and duration) from a preestablished normal, the relay then per-forming a voltageor a current-sensing function.

In an important aspect the invention is concerned with the thermal coupling between a bimetallic arm, for example which carries one of the contacts, and a heater member there-for. One manner of insuring closeness of such coupling involves allowing the heater member to be carried by that arm; this is usually disadvantageous because of the loading which is thereby imposed on that arm, especially in, though not limited to, the case wherein for time-delay purposes that member is to have appreciable thermal capacity and thus mass. On the other hand the alternative mounting of the heater member adjacent to a face of but separately from that arm, 'which inherently must bow transversely to its face, necessarily involves a serious loss of thermal coupling when that aim is bowed away (from the heater member.

According to this aspect of the invention a first end of the heater member is retained adjacent a supported end of the bimetallic arm, while the second end of that member is retained independently of that arm; the heater member has a first portion extending from its first end along a longitudinally substantial portion of the bimetallic arm, and beyond that first portion has a flexible portion; and the regions of the first portion removed from the heater members first end are biased toward the bimetallic arm, thereby to maintain the first portion in mechanical adjacency and close thermal coupling to said portion of the bimetallic arm as that arm bows in greater and less degree.

Preferably the retention of the first end, or of each end, of the heater member is an effectively pivotal retention. 'Permissibly the abovementioned flexible portion of the heater member may be resilient and may be prestressed to elfect the abovementioned biasing. The end of the bimetallic arm opposite to its supported end may 'be a free end, and the supported end may be bimetallically supported in a manner rendering the position of the free end substantially free from influence by ambient temperature. The first portion of the heater member may :be a stiff portion, relatively to the flexible portion. The heater member may further comprise a second relatively stiff portion intervening between its second end and the flexible portion.

In another aspect the invention is concerned with the 3,270,167 Patented August 30, 1966 apt provision of means for appropriately delaying the influence of the heater member on the bimetallic arm. There is on the one :hand known the provision on that arm of suflicient mass, either in the form of thickening of or in the form of attachments to that arm, to accomplish the desired delay; the former of course results in reduction of the displacement of that arm per degree temperature change, and the latter at least in an undesirable loading. On the other hand there is known the use of heat-lagging means in an adjacent independently supported heater member; as heretofore employed, however, such means have involved elements of poor thermal conductivity, with serious adverse effects on the return of the relay upon deenergization to condition for proper reoperation and other unfavorable complications.

According to this aspect of the invent-ion the heater member, typically retained as above set forth, may comprise heataconductive means of substantial heat capacity facing the bimetallic arm, and may further comprise an electrically energizable heater element thermally coupled to, and from which heat is transferred to the bimetallic arm through, such heatconductive means. Such heatconductive means of substantial heat capacity may be comprised in the first portion of the heater member, which portion is maintained in adjacency and close thermal coupling to a portion of the bimetallic arm as that arm bows in greater and less degree. When there are two relatively stiff portions in the heater member such heat-conductive means of substantial heat capacity may be comprised in each.

Still another aspect of the invention is concerned with the proper setting or adjustment of the contacts of the relay relatively to each other so that, if it is to perform a time-delay function, it will operate with the intended delay time or so that, if it is to perform a sensing function, its contacts will be closed by an infinitesimal margin only when the current or voltage supplied to the heater member is at the preestablished normal value. According to this aspect of the invention such setting is accomplished under dynamic conditions-i.e. one of the contacts is withheld from fixation to the element which supports it and is permitted to float in touching relationship to the other contact until the heater member (in the case ofthe time-delay relay, starting with the entire relay at ambient temperature) has been energized for the period of the intended delay, or until the heater member (in the case of the sensing relay) has been energized to saturation of the relay elements by the normal voltage or current, and only then is that contact fixed to its supporting element. Such setting may be effected with respect to a group of relays simultaneously, thereby providing a substantial economic advantage.

Such a manner of contact setting broadly has been employed in thermostats, wherein there is necessarily and inherently present no compensation for ambient temperature. Thermal relays, however, ordinarily present the need for proofing of their structures against the effects of ambient-temperature variations and -a common arrangement for accomplishing this' has beenthe provision, in

addition to the heater-influenced bimetallic arm or equivalent, of a compensating arm or equivalent equally influenced by ambient temperature but unequally (ideally, not at all) influenced by the heater, a respective one of the contacts being carried by each of those two arms or equivalent. members. In such relays any attempt to utilize the manner of contact setting above described has invariably involved undesired loading effects, either of mass or of force or of both, on the member carrying the contact which is to be fixed thereto under the dynamic conditions-loading effects which are always disadvantageous, and of which some will disappear as an incident of the fixation thereby rendering unrepresentative of the conditions later to be presented in use the conditions under which the fixation is effected.

Thermal relays are known in which one contact is carried by a mechanical system which itself comprises both the heater-influenced member and the compensating member. I have observed that in such relays, since the second contact may be carried directly by the base of the relay, that second contact may be set in the manner above described without entailing any deleterious loading either of mass or of force or any unfavorable effects of such loading. Accordingly in this aspect of the invention there is comprised a relay in which the first contact is carried by a mechanical system in which the heater-influenced and compensating members are both comprised, in which the second contact may initially float along an appropriate predetermined line in touching relationship to the first contact, and which includes means for locking the second contact to the base of the relay while that contact is in touching relationship to the first contact under the selected dynamic condition. Such locking may for example be effected by radially contracting helical spring means surrounding an appropriate part of the contact, the effect of which may be initially suspended by appropriate electrically disrupti'ble means which may be disrupted without mechanical access thereto.

Various objects of the invention have been made apparent by the foregoing brief description. Allied and other objects will appear from the following detailed description and the appended claims.

In the detailed description hereinafter set forth reference is had to the accompanying drawings, in which:

FIGURE 1 is a righthand side view, in cross section below the line 22 and therea-bove in elevation with the cover (there indicated in dash-dot lines) removed, of a relay embodying the present invention;

FIGURE 1a is a fractional view corresponding to FIGURE 1 but showing the relay with its bimetallic arm 33 moved by heat to an operating position;

FIGURE 2 is a horizontal cross-sectional view taken along the line 22 of FIGURE 1 and showing the base of the relay of that figure;

FIGURE 3 is a generally vertical cross-sectional view taken along the line 3-3 of FIGURE 1, omitting elements to the rear of the line 44 of that figure other than the heat-lagging blocks 65;

FIGURE 4 is a generally vertical cross-sectional view taken along the line 44 of FIGURE 1;

FIGURES 5a through 5d are elevational views (FIG- URES 5a through 50 being front views and FIGURE 5d being a righthand side view) of component parts of the heater member of the relay of FIGURE 1;

FIGURE 6 is an enlarged generally horizontal crosssectional view taken along the line 66 of FIGUREI;

FIGURE 7 is an enlarged front view of a portion of the relay of FIGURE 1, omitting parts to the rear of the line 3--3' of that figure;

FIGURE 8 is a top plan view of the portion illustrated in FIGURE 7, as seen along the line 88 of that figure;

' FIGURE 9 is a fractional view showing an arrangement alternative to that of a portion illustrated in FIG- URE 8;

FIGURE 10 is a righthand side view similar to a part of the upper portion of FIGURE 1 but illustrating a relay modified in various respects from that of FIG- URE '1;

FIGURE 11 is a generally vertical cross-sectional view taken along the line 11-11 of FIGURE 10; and

FIGURES 12a and 12b are elevational views (FIG- URE 12a being a front view and FIGURE 12b a righthand side view) of component parts of the heater member of the relay of FIGURE 10.

Reference may first be had to FIGURES 1 and 2 for an understanding of the elements which in effect form a base for the further portions of the relay. Herein will be seen a thick glass disc 10 from which there extend upwardly nine glass protrusions (four only of which are seen in FIGURE 1) circularly arranged, angularly spaced by 36 each from the next (except for one gap of 72) and designated generally as 1*1. Vertically through each protrusion as the disc therebelow there extends a respective metallic pin, all nine pins being seen in FIG- URE 2 numbered counterclockwise (starting at 12 oclock) from 1 through 9; all the pins may extend downwardly a substantial distance from the disc 10 for insertion into an appropriate socket (such as a 9-pin miniature radio tube socket), while all the pins other than 2 and 7 may extend upwardly from the respective protrusions 1 1 for a substantial distance.

Closely above the protrusions 11 the vertical central portion 17 of a bracket 14 may be spot-welded to the inner surfaces of pins 8 and 9; from this central portion the more extreme portions of the bracket may be folded respectively toward pins 1 and 6 for a short distance, and then re-folded away from each other to form the vertical bracket end portions 15 and 26 respectively, aligned with each other. The portions 15 and 16 and all but the central part of portion 117 may extend upwardly to a some what greater height than the remainder of the bracket .14, which remainder will form a skeleton shelf; on this shelf may rest a horizontal piece 118 of mica suitably shaped to be retained against lateral movement by the further-upwardly-extending portions 15, 16 and 17. This mica piece 18 may be provided with a plurality of parallel slots 19, one of which may for example be substantially in alignment with the bracket portions 15 and 16 and the other or others of which may be closely spaced and successively nearer the pins 8 and 9.

Against those vertical surfaces of bracket portions 15 and 16 which face away from the pins 8 and 9 there may be spot-welded the right-shown surfaces of downwardly extending end portions of respective arms 31 and 32 of a bimetallic member 30 hereinafter described. To the leftshown surfaces of those arm end portions there may be spot-welded the mutually aligned vertical end portions 21 and 22 of a bracket 20; which between those end portions is shaped into a V having ventica-l side portions 23 and 24 and whose rounded apex 29 is disposed close to pins 3 and 4. From the upper edges of the side portions 23 and 24 there may be folded outwardly generally triangular ears or lugs 25 and 26 respectively, the outer portions of which may be provided with respective holes 27 and 28 axially aligned with but considerably larger than the pins 2 and 5, respectively.

In the base as thus far described the assembly of brackets 14 and 20, into which assembly the. lower end portions of the bimetallic-member arms 31 and 32 are in effect inset, has so far been seen to be supported to the glass disc 10 only by pins 8 and 9; as will hereinafter appear, however, an element rigidly secured to the bracket 20 is spot-welded to the pins 3 and 4, so that the assembly of brackets. 14 and 20 becomes very effectively and rigidly anchored to the glass disc 1-and with it and the mica piece 1 8 forms the base for further relay portions.

Reference to the figures may now conveniently include FIGURE 3. The thermally sensitive portion of the relay may comprise a bimetallic member 30 having at its top a horizontal cross-portion 34; this cross-portion is desirably of angular section normal to its length, in order to restrain it against thermally induced bowing, and accordingly'it is shown comprising a part 35 disposed in a generally vertical plane and a part 36 folded over from the top edge of 35 into a generally horizontal plane. From a common side of the cross-portion 34, specifically from the bottom of the part 35, there extend downwardly a plurality of generally parallel arms, specifically outer arms 31 and 32 and central arm 33, all of which form further parts of the bimetallic member 30. One of thosearms, specifically the central arm 33, may extend down wardly to about the level of the top of bracket and in its lower end portion may carry a contact 40 facing toward pins 3 and 4. At least one other of the arms preferably, and as shown, both the arms 31 and 32, which may extend down somewhat further than arm 33 is or .are secured to the base, thereby supporting the bimetallic member the manner of accomplishing this has already been described.

It is convenient to .provide on the central arm 33, at approximately its vertical mid-point, a very slight bend which will place its lower end portion (and thus contact very slightly nearer the pins 3 and 4, as has been illustrated in FIGURE 1. Further with respect to that central arm, it may be mentioned that it is desirable that its width taper slightly from the cross-portion 34- to the free end of the arm, as has been illustrated in FIGURE 3.

It will be understood that if the central arm 33 only of the bimetallic member 30* be heated, that arm will bow-which it is free to do, and which will displace in progressive degrees its regions progressively remote from the cross-portion 34. If the higher-coefiicient layer of the ibimetallic member face the pins 8 and 9, that bowing will carry the contact 40 along a generally horizontal line toward the pins 3 and 4. On the other hand if all the arms of the bimetallic member be uniformly heated, as by an increase in ambient temperature, the arms 31 and 32 as well as the arm 33 will how; the bowing of 31 and 32 will result in a displacement of the crossportion 34 to the left (as seen in FIGURE 1) and in a counterclockwise reorientation of its generally-verticalsection part 35, thus rocking the arm 33 counterclock- Wise to carry the contact 40 away from the pins 3 and 4. In view of the placement of contact 40 on arm 33 very nearly at the level of emergence of arms 31 and 32 from between the bracket portions 1521 and 16-22 respectively, the contact movement just mentioned will essentially exactly neutralize the contact movement resulting from ambient-induced bowing of arm 33. Thus the bimetallic member 30 forms a mechanical system secured to the base and supporting the contact 40' for substantially linear movement; that system has first and second thermally responsive elements (i.e. arm 33 on the one hand and arms 31 and 32 on the other) to the temperatures of which the position of the contact is oppositely responsive, so that that position becomes substantially independent of any temperature, such as the ambient, which similarly affects arms 33 and 31-32.

It may be mentioned that the compensating action which has just been described is effective not only with respect to temperature influences jointly affecting the several arms but also with respect to other factors, such as distortions occurring in the lower end portions of the arms 31 and 32 where they are held between the bracket portions 15-21 and 1622.

In order approximately to center the cross-portion 34 in the relay, and in view of the fact that the bracket portions 15-21 and 16-22 may position the lower end portions of arms 31 and 32 somewhat to the right of center (as seen in FIGURE 1), it is convenient slightly to bend those arms at their lines of emergence from between those bracket portions, as illustrated in the figures-an expedient which is without effect on the functioning of the relay.

The relay includes an electrically energizable heater member 50 to which one only of the thermally responsive elements, specifically the bimetallic arm 33, is efficiently coupled thermally so that the energization of that heater member will invoke an actual movement of the contact 40. This heater member is an elongated one, appearing in FIGURE 1 to the right of the bimetallic member 30 to which its relationship is hereinafter more fully described. The heater member of course includes an electrically energizable heater element; in the form shown. in FIGURE 1 and which will first be described it also includes heat-lagging means comprising heat-con- 6 ductive material of substantial heat capacity, hereinafter further mentioned. The heater member 50 is itself seen in elevation in FIGURE 4; its typical components, however, are shown in elevation in FIGURES 5a through 5d, and reference may conveniently first be had to the latter figures.

In FIGURE 5a there is shown a generally rectangular thin piece 51 of mica notched at each of its four corners and having an extended longitudinal mid-portion 52 of reduced width; into appropriate small slots in the piece 51 there may be threaded nickel ribbons 54 whose end portions may for example be exposed on the front of that piece. A second identical piece (lacking the ribbons 54) may be placed behind the piece 51, and about the pair of pieces in their mid-portion 52 there maybe wound a wire 55 of suitable resistance characteristics to form the heater proper, the two ends of the wire being spotwelded to the respective ribbons 54. In FIGURE 5b there is shown a piece 56 of mica similar to piece 51 but not quite as wide and not of reduced-width mid portion; two of these pieces 56 may be placed in front of and two more behind the pieces 51 and winding 55' to form a multi-layer sandwich.

In FIGURES 5c and 5d there is shown a generally rectangular springsteel strip whose main portion may be of the same length as that of the mica pieces 51 and 56 and of the same width as that of the end portions of those pieces after their corner notching. Retaining straps 59 of soft metal may be spot-welded to the face of the strip 60 across the ends of its main portion, and a retaining strap 58 of similar material may be spotwelded to that face across its longitudinal midpoint. The sandwich described in the preceding paragraph may be placed behind the strip 60; the straps 59 may be folded around the sandwich at the corner notches, and the strap 58 folded therearound at the mid-section, to result in a secure assembly. In the interest of clarity FIGURE 1 greatly exaggerates the thickness of the sandwich, which will actually be a very minor part of the thickness shown in that figure.

In the heater member 50 the heat-lagging means may comprise two blocks of thermally onductive material of substantial heat capacity, such as brass, these blocks being spot-welded to the face of the strip 60 and each extending from near a respective one of the straps 59 to near the strap 58. The width of the blocks may be about the same as the width of the central bimetallic arm 33 near the supported end of the latteri.e. the end at which it merges into the cross-portion 34 ofmember 30. a

member 63 (see especially FIGURE 6) whose central leg may be spot-welded to the top of the part 36- of cross-portion 34 (this ordinarily being done as a final act in the mechanical assembly of the heater member to the rest of the structure) and against whose cross-arm those ears may be in contact.

Means are provided, to retain the other or second end of the heater member, independent of the bimetallic arm 33. Those means may take the form of a single ear 61 extending downwardly from the bottom of the strip 60, together with one of the slots 19 with which the mica piece 18 was above stated to be provided and through which the car 61 may extend downwardly (the insertion of that ear therein ordinarily being the initial act in the mechanical assembly of the heater to the rest of the structure), that slot being positioned or chosen so that the lower end portion of the front or exposed surface of ship to the bimetallic arm 33 will be reverted to following a description of its electrical connection in the relay. Such connection may be by means of the nickel ribbons 54, which may project forwardly (as seen in FIGURE 1, left- Wardly) from near the bottom of the heater member; those ribbons may pass between the end portion of the bimetallic arm 33 and the arms 31 and '32 respectively, as indicated in cross section in FIGURE 3 (but omitted from FIGURE 1 in the interest of simplicity of that figure) and may be electrically connected to the respective pins 1 and 6. It will be understood that if current be passed through the heater element 55 the entire heater member 50 will be heated, and heat will be transferred from it to the bimetallic member -relatively efficiently to the bimetallic arm 33 and relatively inefficiently to the arms 31 and 32-and that the very substantial resulting excess of temperature of bimetallic Ell 11163 over that of arms -31 and 32 will result in bowing of the bimetallic arm 33 and movement of the contact 40. Still assuming the abovementioned arrangement of the bimetallic member wherein its higher-coefficient layer is disposed toward the heater member, the bowing of the bimetallic arm 33 and the movement of the contact may be toward such positions as are illustrated in FIGURE 1a. Such bowing of the arm 33 is of course in a direction to carry that arm in general away from the heater member and thus appreciably to weaken its thermal coupling to that member, this being a result of the described retention of the heater member in the relaywhich, however, has definite advantages for reasons introductorily brought out.

During original assembly the T-shaped member 63 may be secured in such a position that the upper block 65 is then retained substantially in contact with the upper portion of the bimetallic arm 33; thus a first portion of the heater member (i.e. the upper portion, including block 65) then extends from the first (upper) end of the heater member along a longitudinally substantial portion (i.e. the upper approximate half) of the bimetallic arm 33. In order largely to retain the originally tight thermal coupling of that arm to the heater member in spite of the thermally induced bowing of that arm, I provide that member with a flexible portion beyond (in FIGURE 1, below) its abovementioned first portion-such flexible portion in the heater member of FIGURES 1 through 6 being the central portion of the springsteel strip between the blocks -and I bias the regions of that first portion of the heater member removed from its first end (e.g. the various regions of the upper part other than that immediately at the retained top end itself) toward the bimetallic arm. The result is that the first portion of the heater member continues to remain in mechanical adjacency to the bimetallic arm, as described during assembly at the beginning of this paragraph, throughout the abovementioned longitudinally substantial portion of that arm, and in close thermal coupling to that portion of the arm, in spite of the bowing of the arm in greater and less degree.

As a biasing means I may utilize the springsteel strip 60 itself. Thus that strip, preferably before the assembly thereto of the sandwich, may be formed by bending at its longitudinal midpoint into a wide V, as indicated by the dash-dot lines in FIGURE 5d, for example with an included angle 0 at the rear of the strip of the order of 170it being noted that the substantial .gap at that part of the strip between the blocks leaves the strip there still flexible as well as free for this bending even though the blocks may have been first secured to the strip.

It may be mentioned that the temperature of the abovementioned upper portion of the bimetallic arm 33, which is the root portion of the cantilever which that arm forms, is the principal determinant of the degree of howing of that arm and of the contact movement, so that the efficiency of thermal coupling of arm to heater member is in a significant sense retained in very major degree in spite of the thermally induced bowing of the arm.

The actiondescri-bed in the preceding few paragraphs would in at least considerable degree be frustrated if one or both end portions of the 'heater member were clamped by their respective mounting arrangements or otherwise inhibited against rotative movement. It is to avoid such frustration that each of those mounting arrangements is limited in function to restraining its respective end portion of that member against lateral or substantial vertical displacement, and does not inhibit rotation of that end portion through a substantial angle--in other word the retentions of the ends of the heater member are effectively pivotal retentions.

A typical end function of the relay is to effect, at the expiration of a period of time following the inception of current sup-ply to the heater member or under some other circumstance introductorily described above, an alteration of the relationship of the contact 40 to another contact. In FIGURES 1 and 1:: such an other or second contact is shown as 41 which, at least after initial adjustment, will be fixed to the base of the relay.

In the illustrated embodiments of the invention the second contact is supported on and electrically connected with a metallic platform which in turn is partially supported by and electrically connected with pins 3 and 4 abovementioned. Reference being had to FIGURES 7 and 8 as well as to FIGURE 1, there will be seen this metallic platform 70 having semicircular ends each centered on the axis of a respective one of the holes 27 and 28 of lugs 25 and 26, above which holes the platform 70 is provided with still larger holes 71 (of which only the one above lug hole 27 actually appears in the figures). The platform 70 is secured to but insulated from the lugs 25 and 26. To provide such insulation there may be positioned immediately below the platform 70 a thin mica piece 67 somewhat larger in area than the platform, and immediately above the platform a generally similar mica piece 68. From the front and rear edges of the platform 70 there may be formed upwardly the respective lugs 72, and 73, the central plane of each being preferably aligned with the respective edge of the plat-form, and it will be understood that the upper mica piece 68 will be suitably notched so that its central portion just fits between and at the sides of those lugs. The mica pieces 67 and 68 may each be provided with holes in alignment with and of the same size as the lug holes 27 and 28. Metallic eyelets 66 may extend upwardly through the respective lugs 25 and 26, through the respective holes in the lower mica piece 67, through the respective platform holes 71, through the respective holes in the upper mica piece 68, and through respective metallic washers 69 immediately above piece 168, against which Washers they may be respectively peened over to secure the platform 70 to the lugs 25 and 26.

The lateral position of the upper mica piece 68 is fixed by the eyelets 66, while that of the platform 70 is fixed by the fitting of that piece 68 against the platform lugs 72 and 73-and when thus fixed the lateral platform position is such as to keep the walls of the oversize platform holes 71 free of contact with the eyelets 66 and thus insulated from the base lugs 25 and 26. The parts are appropriately proportioned so that the upper portions of the pins 3 and 4 are tangent to the forward (as seen in FIGURE 1, leftward) surface of the forward platform lug 72, to which those pins may be spot-welded. Since the platform 70 from which that lug extends is by the eyelets 66 rigidly secured to the lugs 25 and 26 of the bracket 20, this fastening of the lug 72 to the pins 3 and 4 completes the very effective rigidification of the base, early above described, of the relay. It will of course be understood that the lower mica piece 67, as Well as the upper one 68, will be appropriately shaped so as not to be interfered with by the pins 3 and 4.

Through the platform lugs 72 and 73, which have just been seen to be altogether rigid with respect to the base of the relay, the second contact is carried by that base.

9 To provide for this the lugs 72 and 73 may be provided with respective holes in horizontal alignment with each other and with the contact 40 along a front-and-back line. Through these holes may just freely pass a cylindrical shank which forms a forwardly extending part of the contact 41. Thus fundamentally the contact 41 will be movable toward and away from the contact 40 along a line which, being a horizontal front-and-back one, is oriented similarly to the line along which contact 40 is movable by bimetallic arm 33.

The contact 41 may be held in a selected position along that line, for example, by a radially contracting helical spring means comprising a spring 45 so formed from a U-shaped piece of spring wire that each leg of the U, somewhat nearer to its free end than to the central portion 46 of the U, has a respective helical portion 47 which when the spring is unconstrained has for example about 1% turns and whose internal diameter is then very slightly less than'the diameter of the contact shank 42; the leg-to-leg dimension (including the leg thicknesses) of this formed spring may be appropriate for the spring just to fit between the platform lugs 72 and 73. The spring may be placed between those lugs, with its helical portions aligned with the holes of those lugs and its free end portions 48 extending horizontally from the bottoms of those holes in the direction of pin 2; those end portions may then be spot-welded to the respective lug surfaces.

In the absence of the contact shank the position of the central portion 46 of the spring may be the more leftwardly of the two indicated in FIGURE 7 by dash-dot lines; the internal diameter of the helical portions 47 will then be slightly too small to admit the contact shank. If now that central portion be swung in the direction of pin 5 (counterclockwise as seen in FIGURE 7) the helical portions 47 will be expanded, and when the central portion 46 has approached the position solidly illustrated in FIGURE 7 that diameter will admit the contact shank. If the springs central portion then be released the helical portions 47 will radially contract and grip the contact shank; the central portion 46 will then have reached a position such as the intermediate one illustrated in FIG- URE 7, and will there remain.

Since the specific contact-securing means and procedures are not necessary incidents of the practice of the earlier aspects of the invention, further description thereof is deferred until the conclusion of this specification.

The structure thus far described, incorporating the heatconductive blocks 65 as heat-lagging means, is of course appropriate to a relatively longer time delay, resulting from the increase which those blocks effect in the thermal capacity of the heater member-an increase effected in a position insuring that that capacity must be filled as a prerequisite to heating of the bimetallic arm 33. It is to be noted that the increase of time delay is effected almost wholly by reason of heat capacity, and with essentially no reliance on poor heat conductivity (which if present seriously delays the return of the relay, on deenergization, to condition for proper reoperation and entails other complications); that it is effected, as brought out above, without serious interference with the closeness of thermal coupling between heater member and bimetallic arm; and that it is on the other hand effected without in any way stiffening or loading the bimetallic armwith the result that both the ultimate arm temperature and contact-40 displacement, as well as the force with which that displacement occurs, are relatively unaffected. The magnitude of influence afforded by the blocks 65 on the time delay of the relay is very nearly proportional to the ratio of the aggregate thermal capacities of those blocks and of the arm 33 to that of the arm 33 alone. Conveniently the elevational areas of the blocks may be standardized and variations in their thickness used to affect their thermal capacities, and thus the time delay of the relay, over a rather wide range.

There are of course many uses which will call for a short delay (or, in the case of sensing devices, a rather quick response) and for such uses the heat-lagging means may be omittedpreferably with a minimization of the thickness of the spring-steel strip (eg 60) and its repositioning so as no longer to be interposed between the heater element 55 and the bimetallic arm 33. A relay in which such changes have been made has been fractionally illustrated in FIGURE 10. By way of example that relay is contemplated as having normally closed contacts to be opened by the act-ion of the relayin contrast to the relay of FIGURE 1 which was contemplated as having normally open contacts to be closed by the relays actionbut there is implied no necessary relationship between the normal condition of the contacts and the presence or absence of the heat-lagging means.

The relay of FIGURE 10 may be basically similar to that of FIGURE 1, the essential differences lying in the bimetallic member (therein designated as 130) and in the heater member (therein designated as 150). The bimetallic member 130 may be of similar front elevation to that (shown inFIGURE 3) of the member 30 and its outer arms 131 and 132 may be terminally held between lug portions 15-21 and 16-22 just as were the outer arms of member 30; its high-expansion side will, however, be directed forwardly (i.e. toward the pins 3 and 4), and its central arm 133 may be formed arcuately so that when the member 130 is at normal room temperature and the locking means constituted by spring 45 is out of operationboth of which conditions have been assumed in the showing of FIGURE 10the side elevational configuration of the arm 133 will be generally similar to that (shown in FIGURE 1a) of the arm 33 when the contact 40 has been moved just to touch the contact 41.

The heater member 150 is seen in front elevation (along line 11-11 of FIGURE 10) in FIGURE 11; its components may be the multi-layer sandwich above described, together with the altered springsteel strip seen in front and side elevations in FIGURES 12a and 12b respectively. This strip, preferably of thinner material than strip 60 but in outline similar thereto, may be provided with two rearwardly formed longitudinal ribs 85, one from near its upper extremity to a little above its midpoint and the other from a little below its mid-point to near its lower extremity, which stiffen its upper and lower halves respectively; it may carry retaining straps 79 and 78 respectively similar to 59 and 58 carried by strip 60, but they may be spot-welded to its rear rather than to.

its forward surface. The strip 80 may 'be formed by bending at its longitudinal mid-point (i.e. between ribs into a rather wide V, as dottedly illustrated in FIGURE 12, "for example with an included angle 5 at the rear of the order of 160 (to result, with the thinner strip, in a generally similar stress of its mid-portion). The sandwich may be placed in front of (rather than behind.) the strip 80, and the straps 79 and 78 then folded forwardly around its end portions and its central portion respectively to result in the heater member 150. The strip 80 will be formed with a bottom ear 81 and top ears 82 (similar to 61 and 62 on 60), and these may be used similarly to 61 and 62 to retain the heater member in the relaybut now with the sandwich itself disposed toward the arm 133 and, in its upper portion, in substantial contact with the upper portion of that bimetallic arm.

Attention may now be redirected to the spring 45 above described and to the aspect of the invention finally stated in the introduction.

It will 'be appreciated that if the central portion 46 of the spring be held in the solidly illustrated position (see FIGURE 7) the locking operation of the spring will be suspended and the contact 41 will be unlocked and thus free to move axially of its shank 42 and of the lug holes in which that shank is retained. In the operation of initial manufacture of the relay I may provide means which holds the spring portion 46 in the solidly illustrated position and which thus suspends the operation of the locking means. This suspending means may take the form simply of a thin metallic wire 49 secured at one end to the springs central portion 46 and at the other end to the upper portion of pin which for the purpose may extend upwardly through the respective eyelet 66 (insulated therefrom by a sleeve 76 of material such as Tefion) and may in its top portion be folded to extend diagonally away from the contact shank 42--the wire 49 being held in tension by the constrained spring 45. The wire 49 may be readily disruptible by the passage of an electric current through it; such passage may readily be eifected by connection of an appropriate source of current between pin 5 on the one hand and either or both of pins 3 and 4 on the other.

If desired the wire 49 may be replaced by a pair of wires 49a and 4% each secured at one of its ends to a respective side of the central spring portion 46 and at the other to pin 5; after that securing the central portion 46 may be cut through, between 49a and 49b, so as to leave two independent springs 45a and 45b in place of 45. This, illustrated in FIGURE 9, especially positively insures locking action by each independent spring portion.

The relay after its initial manufacture (and preferably before the disruption of the wire 49 or of the wires 49a and 4912) may if desired be enclosed by a glass envelope (not shown) fused to the glass disc and then evacuated, filled with any desired atmosphere and sealed off in conventional manner to afford a hermetically sealed enclosure of the relay. Alternatively and as illustrated in FIG- URE 1, there may be positioned about the marginal portions of the glass disc 10 (which portions may for example be somewhat thinner than the main portion of the disc) upper and lower metallic ferrules 12 having flanges which lie against and may be spot-Welded to each other, preferably with a resilient gasket 13 intervening between the top of the disc 10 and the upper ferrule 12, and an inverted deep-cup-shaped metallic cover C may then be peripherally crimped to the flanges of the ferrules to afford a dust-tight (though not hermetically sealed) enclosure.

When desired, ordinarily after the enclosure of the relay, the contact 41 may be locked to the base of the relay in that position which is proper for the intended function of the relay. For this purpose the relay may be plugged into a socket arranged in a vertical plane with the holes which admit pins 8 and 9 disposed at the bottom, so as to render vertical the axis of the contact shank 42 with the contact directed downwardly and therefore by gravity biased to touch contact 40. (Alternatively, although not preferably, a light spring, not shown, terminally secured as to the lug 72 may be used to bear against the end of shank 42 and thus to bias the contact 41 toward contact 40 irrespective of the orientation of the relay.)

The proper voltage may then be applied across, or the proper current then supplied to, to heater element for that length of time which is appropriate to the intended use of the relay, and the wire 49 (or wires 49a-49b) then disrupted in manner above disclosed; if the relay is to function as a time-delay relay that time will be that of the intended delay, while if the relay is to function as a sensing device that time will be one ample to insure thermal saturation of the heater member 50. It will be understood that in this operation as the contact 40 is moved by the 'bimetallic arm 33 under the influence of the heater member 50, contact 41 will remain in touching relationship to and will move with it-until this action of the latter contact is deliberately terminated by the disruption of the wire or wires. The contact 41 having thus been adjusted under the actual operating conditions for which the relay is intended, there is insured in the later operation of the relay a high degree of accuracy.

It will be observed that when the locking means (i.e. the radially contracting helical spring or springs) is rendered operative its dynamic action is a circumferential gripping of the contact shank 42which may possibly no influence whatever on that contact in an axial direc- .tion, thus insuring that there will be no displacement, even minute, of the contact 41 from the position in which it is intended that it be locked. It will further be appreciated that the locking means and. its disruptible wire or wires exert no loading effect, either of mass or of force, on any contact or part whose position is varied either by ambient temperature or by the heater member 50, there being only one such contact40and the effect of the locking means being only on the other contact 41.

The last preceding six paragraphs have spoken in terms of the relay of FIGURES 1 through 6. In the case of the relay of FIGURES 10 through 12 the contact 41 may be brought into proper position, and then locked, in a quite analogous manner. Again in the process the contact 41 may be downwardly directed; as the contact 40 is moved downwardly (rightwardly as itappears in FIG- URE 10) under the influence of the heating of arm 133 the contact 41 will move downwardly with it. When the proper position has been reachedthat position being for example one in which the arm 133 and contact 40 are approximately in the configuration and position of arm 33 and contact 40 as shown in FIGURE 1-the contact 41 will be locked; thereafter the next infinitesimal portion of the continuing movement of contact 40 will constitute the intended opening of the contacts.

While I have shown and described my invention in terms of particular embodiments thereof, it will be understood that I thereby intend no unnecessary limitations. Modifications in many respects will be suggested by my disclosure to those skilled in the art, and such modifications will not necessarily constitute departures from the spirit of the invention or from its scope, which I undertake to define in the following claims.

I claim:

1. In combination in a thermal relay: a bimetallic arm having a supported end, said arm being bowable in response to applied heat, an elongated heater member, means for retaining a first end of the heater member adjacent said supported end of the bimetallic arm, and means independent of the bimetallic arm for retaining the second end of the heater member, the heater member comprising a first portion extending from said first end along a longitudinally substantial portion of the bimetallic arm and further comprising a flexible portion beyond said first portion, the regions of said first portion of the heater member removed from said first end being biased toward the bimetallic arm whereby to maintain said first portion in mechanical adjacency and close thermal coupling to said portion of the bimetallic arm as that arm bows in greater and less degree.

2. The subject matter claimed in claim 1 wherein said heater member comprises an electrically energizable heater element.

3. The subject matter claimed in claim 1 wherein the retention of said first end of the heater member by said first-recited retaining means is an effectively pivotal retention.

4. The subject matter claimed in claim 1 wherein said flexible portion is resilient and is stressed to effect said biasing.

5. The subject matter claimed in claim 1 wherein the end of said bimetallic arm opposite to said supported end is free, and wherein said supported end is bimetallically supported in a manner rendering the position of said free end substantially free from influence by ambient temperature.

6. The subject matter claimed in claim 1 wherein said first portion of the heater member is a relatively stiir' portion.

7. The subject matter claimed in claim 6 wherein said heater member further comprises a second relatively stiff portion intervening between its second end and said flexible portion.

8. The subject matter claimed in claim 1 wherein said heater member comprises heat-conductive means of substantial heat capacity having a surface facing the bimetal lic arm, and wherein said heater member further comprises an electrically energizable heater element which faces the opposite surface of, and from which heat is transferred to the bimetallic arm through, said heat-conductive means.

9. The subject matter claimed in claim 7 wherein each of said two portions of the heater member comprises heat-conductive means of substantial heat capacity having a surface facing the bimetallic arm, and wherein said heater member comprises an electrically energizable heater element which faces the opposite surface of each of, and from which heat is transferred to the bimetallic arm through, said heat-conductive means.

10. In combination in a thermal relay: a base, a first contact, a mechanical system secured to the base and supporting said first contact for movement along a first line, said system comprising first and second thermally responsive elements to the temperatures of which the position of said contact is oppositely responsive whereby to render said position substantially independent of ambient temperature, an electrically energizable heater element thermally closely coupled to one only of said elements, a second contact, a support, carried by the base, in which said second contact is retained for movement into and out of touching relationship to said first contact along a second line at least substantially coincident with said first line, and means, connected with the base and actuable when said second contact is in touching relationship to said first contact and the heater member is in a selected state of energization, for locking said second contact with respect to the base, said second contact being freely movable along said scond line in the absence of action of said locking means.

11. The subject matter claimed in claim 10 wherein said locking means is biased to action, further including electrically disruptible means suspending the action of said locking means.

12. The subject matter claimed in claim 10 wherein said second contact includes a shank whose axis lies on said second line, and wherein said locking means comprises radially contracting helical spring means surrounding said shank.

13. The subject matter claimed in claim 12 further including an electrically disruptible wire holding said helical spring means radially expanded.

14. The subject matter claimed in claim 10 further including a mechanically impenetrable cover enclosing the relay, and wherein said locking means is actuable from exteriorly of the enclosed relay.

References Cited by the Examiner UNITED STATES PATENTS 908,679 1/ 1909 Kelley 200-122 1,447,194 3/1923 White 200-122 X 1,780,302 11/1930 Koch et al. 200-122 1,935,909 11/1933 Koch 200-122 2,171,895 9/1939 Sardeson 200-133 2,199,638 5/1940 Lee 200-122 2,446,307 8/1948 Shaw 200-122 2,609,466 9/ 1952 Blonder 200-113 2,639,190 5/ 1953 Sitzer 200-113 2,643,061 6/1953 Johnson 200-122 2,777,032 1/1957 Burch 200-113 2,854,548 9/ 1958 Cassidy 200-122 2,859,305 11/1958 Happe 200-122 2,936,354 5/1960 Greig 200-122 2,939,933 6/1960 Manganaro et al 200-122 2,997,681 8/ 1961 Klassen 339-184 3,031,551 4/1962 White et al. 200-122 3,078,360 2/1963 Ulanet 200-122 3,084,237 4/1963 Mentzer 200-138 3,147,354 9/1964 Hewitt 200-122 FOREIGN PATENTS 347,007 4/ 1931 Great Britain. 446,672 4/ 1936 Great Britain.

BERNARD A. GILHEANY, Primary Examiner.

L. A. WRIGHT, Assistant Examiner. 

1. IN COMBINATION IN A THERMAL RELAY: A BIMETALLIC ARM HAVING A SUPPORTED END, SAID ARM BEING BOWABLE IN RESPONSE TO APPLIED HEAT, AN ELONGATED HEATER MEMBER, MEANS FOR RETAINING A FIRST END OF THE HEATER MEMBER ADJACENT SAID SUPPORTED END OF THE BIMETALLC ARM, AND MEANS INDEPENDENT OF THE BIMETALLIC ARM FOR RETAINING THE SECOND END OF THE HEATER MEMBER, THE HEATER MEMBER COMPRISING A FIRST PORTION EXTENDING FROM SAID FIRST END ALONG A LONGITUDINALLY SUBSTANTIAL PORTION OF THE BIMETALLIC ARM AND FURTHER COMPRISING A FLEXIBLE PORTION BEYOND SAID FIRST PORTION, THE REGIONS OF SAID FIRST PORTION OF THE HEATER MEMBER REMOVED FROM SAID FIRST END BEING BIASED TOWARD THE BIMETALLIC ARM WHEREBY TO MAINTAIN SAID FIRST PORTION IN MECHANICAL ADJACENCY AND CLOSE THERMAL COUPLING TO SAID PORTION OF THE BIMETALLIC ARM AS THAT ARM BOWS IN GREATER AND LESS DEGREE. 